'America Cannot Be Intimidated': Trump Speaks on 9/11 Attack

President Donald Trump and first lady Melania Trump joined Secretary of Defense James Mattis at the Pentagon on the 16th anniversary of the Sept. 11 attacks. Trump, a native New Yorker, spoke out against the "savage killers" who perpetuated the attacks, saying "America cannot be intimidated." (Published Monday, Sept. 11, 2017)

Leading his first commemoration of the solemn 9/11 anniversary, President Donald Trump said Monday that "the living, breathing soul of America wept with grief" for each of the nearly 3,000 lives that were lost on that day 16 years ago.

Addressing an audience at the Pentagon, one of three sites attacked on Sept. 11, 2001, Trump used the anniversary to sternly warn terrorists that "America cannot be intimidated." He said those who try are destined to join a long list of vanquished enemies "who dared to test our mettle."

Trump and first lady Melania Trump observed a moment of silence at the White House on Monday at the exact moment that a hijacked airplane was slammed into the World Trade Center. The Trumps bowed their heads and placed their hands over their hearts as "Taps" rang out across the South Lawn. They were surrounded by White House aides and other administration officials in what has become an annual day of remembrance.

Nearly 3,000 people were killed when hijackers flew commercial airplanes into New York's World Trade Center, the Pentagon and a field near Shanksville, Pennsylvania.

American Flag Unfurled at Pentagon to Commemorate 9/11

Sept. 11 commemorations got underway in the D.C. area at dawn with the unfurling of an American flag down the side of the Pentagon. The tradition began the day after the Sept. 11 attacks in 2001 when firefighters unexpectedly got onto the building's roof and draped a large flag across the damaged building -- a quiet symbol of America's determination.

(Published Monday, Sept. 11, 2017)

Trump, a native New Yorker who was in the city on 9/11, said the attack was worse than the Japanese assault on Pearl Harbor during World War II because it targeted civilians. He vowed that it would never be repeated.

"The terrorists who attacked us thought they could incite fear and weaken our spirit," Trump said later at the Pentagon, where he was joined by Defense Secretary Jim Mattis and Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff. "But America cannot be intimidated and those who try will join a long list of vanquished enemies who dared test our mettle."

He said that when America is united, "no force on earth can break us apart."

Trump also offered words of comfort the many whose loved ones perished in the attacks.

"For the families with us on this anniversary, we know that not a single day goes by when you don't think about the loved one stolen from your life. Today, our entire nation grieves with you," Trump said. Later, he said "the living, breathing soul of America wept with grief for every life taken on that day."

Vice President Mike Pence was representing the administration a ceremony at the 9/11 memorial in Shanksville.

From the Archives: The Man With the Red Bandanna

At the dedication of the 9/11 museum in May 2014, President Obama recalled the heroism of Welles Crowther, a 24-year-old from Nyack, New York, who perished on 9/11 while saving the lives of others. On the first anniversary of the attacks, NBC 4 New York's Chuck Scarborough talked with Crowther's parents who explained how they came to learn their son was the hero known only at first as "the man in the red bandanna." The museum has one of Crowther's red bandannas on display.

(Published Sunday, Sept. 10, 2017)

Trump has a checkered history with 9/11. He frequently uses the attack to praise the city's response but has also made unsubstantiated claims about what he did and saw on that day.

Trump often lauds the bravery of New York police officers, firefighters and other emergency responders who rushed to the Twin Towers to help as an example of the resilience of the city where he made a name for himself.

But he has also criticized President George W. Bush's handling of the attacks, accusing Bush of failing in his duty to keep Americans safe.

Trump has made dubious claims about Sept. 11, particularly saying when talking about Muslims that "thousands of people were cheering" in Jersey City, New Jersey, across the Hudson River from lower Manhattan, as the towers collapsed. There is no evidence in news archives of mass celebrations there by Muslims.

Trump also said he lost "hundreds of friends" in the attack and that he helped clear rubble afterward. Trump has not provided the names of those he knew who perished in the attack, but has mentioned knowing a Roman Catholic priest who died while serving as a chaplain to the city's fire department.

Associated Press writer Ken Thomas in Washington also contributed to this report.